i am unsure where your are from but maybe its because i work in the gay scene or maybe its different in toronto than other places but tranny is kind of like the word jew what turns it into a slur is the way you say it they call the tranny performances tranny shows and the trannys refer to themselves as such and all the staff refer to them as such as well as in the gaybeirhood the tranny competitions are called those on flyers for the events now thats within the gay scene im sure if a ignorant person was like hey you fucking tranny it would be taken as a slur no doubt